Mini Kossel first test problems
January 05, 2015 08:27AM
Hi Guys

I am having problems with my Mini Kossel and not sure what the problem is or how to solve it. I'm completely new to 3D printing so be kind

Please see my other thread here

Regards
Dave
Re: Mini Kossel first test problems
January 05, 2015 06:14PM
I just watched the video, that helped.
It looks like your feed rates are too high when homing. I'd suggest lowering the homing feedrate, and lowering the acceleration.

Hope that helps.


My printer: Raptosaur - Large Format Delta - [www.paulwanamaker.wordpress.com]
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Re: Mini Kossel first test problems
January 06, 2015 03:50AM
I'm not sure how to do that but I'll try and figure it out

Thanks
Re: Mini Kossel first test problems
January 06, 2015 04:45AM
It looks to me that your motors are moving correctly at low speeds but not at high speeds. To test this theory, repeat the first test you did, but try higher values of the F parameter. Find the highest value that gives correct movement. My Mini Kossel can go up to at least 15000.

To get higher feedrates working, check the current settings on the stepper drivers, and try reducing the acceleration setting as already suggested.

If you still can't get good speeds, this could mean that you are using low current/high inductance stepper motors and they are not getting enough voltage. What stepper motors, controller electronics and power supply are you using?

Edited 1 time(s). Last edit at 01/06/2015 04:48AM by dc42.



Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].
Re: Mini Kossel first test problems
January 06, 2015 04:46PM
I've made a little progress tonight. I've changed some acceleration values from 200x60 to 50x60 and now it will home. Its probably too slow though.

I'm using NEMA17 stepper motors. The power supply that came with the kit is 12V 5A but I heard this was enough so I am using a 12V 10A supply that I already own. I'm not sure if this is suitable? The controller electronics came with the kit and are RAMPS 1.4, Mega 2560 Controller, A4988 Stepper Motor Driver.

I tried to upload the Configuration.h file that Joshua from Makergeeks sent me but it returned errors so I'm using the one from here Mini Kossel (RAPMS). Is there a more suitable one to use as a basis?
Re: Mini Kossel first test problems
January 06, 2015 05:11PM
A 10A power supply is quite likely still not enough, depending on the resistance of your heated bed. If you have a multimeter, measure that resistance. Use Ohms' law to work out the heated bed current, then add at least 7A and preferably 10A for the hot end, stepper motors and electronics. Typical 3D printers with heated bed need a 20A power supply, although as the MK has quite a small bed, it may manage with a bit less. You can get a 12V 20A or 25A power supply quite cheaply on eBay. I paid about GBP21 for my 25A one.

However, assuming that the heated bed is turned off during testing, that doesn't explain the homing problem. So I refer to my previous reply. Have you checked that the pots on the stepper driver modules are set to the right current for your stepper motors?

Nema 17 is just a size, not a full specification. Look for a model number on a plate on the side of the motor, and then Google that for the specification.

Edited 2 time(s). Last edit at 01/06/2015 05:16PM by dc42.



Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].
Re: Mini Kossel first test problems
January 07, 2015 03:10AM
I've just ordered a new 30A power supply so I can rule out any problems caused by that smiling smiley

Currently my extruder motor makes a buzzing but will not move. I hope this is related to the lack of current too?
Re: Mini Kossel first test problems
January 07, 2015 04:13AM
Quote
daveflave
Currently my extruder motor makes a buzzing but will not move. I hope this is related to the lack of current too?

Can you move the extruder gear easily by hand when the power is off? If so, then the problem probably isn't lack of current, it means that only one of the two stepper motor phases has been energised. This can be caused by a faulty stepper motor, cable, or driver. The first two are easy to check with a multimeter. The driver can be checked by swapping the extruder driver module on the RAMPS with one of the others.

Edited 3 time(s). Last edit at 01/07/2015 04:15AM by dc42.



Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].
Re: Mini Kossel first test problems
January 07, 2015 04:18AM
I'll try it tonight and let you know.

I'd be completely lost without this forum. Thank you so much for the help
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